This is my first thread here, and I want to say that I think this forum seems to have a nice group of members.
I became the owner of a 2001 Honda Insight 6 days ago. I work as a power generation engineer for Microsoft, and before this job, I worked in the racing engine part design for 7 years.
I bought the car with the intent of swapping the engine to a Honda k24a2, however, I think it would be much more a challenge to reach my power goals with the stock engine.
The stock engine is very de-tuned. Specific output (hp/L) is very low, which is to be expected for an engine that has a 6200rpm ceiling, but this doesn't explain the low specific torque (ft-lbs/L).
On an engine with so many outstanding and exotic measures taken to reduce Fmep (frictional loss), I expected to see excellent BSFC (brake specific fuel consumption). (BSFC is the measure of how much useful energy an engine creates per unit of fuel.) I was dissapointed.
I started to design a cam profile better optimized towards my needs, and I was very thrilled with the mechanical limits and properties of the valvetrain. I also measured the stock (true lift) lift at the valves.
First, some pictures of our beautiful valvetrain design. If you note the use of needle bearings in most piviots (excludeing intake rocker shaft piviot which appears to be a bushing), the use of forged aluminum exaust rockers, and other weight saving measures, you will see that no expense was spared in its construction.
Above picture.
http://www.ejlin.com/albums/album41/DSCF0601.sized.jpg
[mod edit: Removed img function. Please see the rules. Links to appropriate pics always welcome]
Picture of beautiful forged aluminum exaust rockers. Note the thin washers to retain the needles on each side of the rocker where it mounts to the shaft.
http://www.ejlin.com/albums/album41/DSCF0607.sized.jpg
This picture shows the primary rocker with its needle roller, and the vtec-e rocker cuddled up against it. The little nubbin on the upper corner of the vtec-e rocker is the houseing for the vtec pin mechanism.
http://www.ejlin.com/albums/album41/DSCF0608.sized.jpg
Here is a measurement of peak exaust valve lift. It's unreadable in the picture, but peak exaust valve lift was 0.300" (limted to +-0.01" precision of fixture)
http://www.ejlin.com/albums/album41/DSCF0606.sized.jpg
This picture shows the measureing of peak intake valve lift. The depth of field for the camera was not able to capture the dial in a readable form, but the lift was 0.322".
http://www.ejlin.com/albums/album41/DSCF0605.sized.jpg
Now, for the most important data. Unlike many engines, the peak lift is not limited by coil bind, but rather by the bottoms of the keeper tangs contacting the upper edge of the valve stem seal. This occurs at roughly 0.610" of lift. This is a massive amount of lift for an engine with such such a small valve face, much beyond the areas of diminishing returns in reguards to valve lift vs increased flow. The clearence around the lobes of the cam in the head was also generously recessed, and I see no reason why the engine can't easily handle a cam with lift pushed into the 0.500" range. I will be doing this when I purchase a spare insight engine and have the camshaft spray welded to build up the lobe enough to have adquate material to work with with out needing to reduce the base circle (which would effect ramp-rate angles in a negative way).
Also, as far as tossing in a cam with more lift and duration on the stock engine, I belive you would be loseing power. I measured stock exaust pressure at peak RPM to be 7psi in the manifold! This is as poor of an IMP to EMP ratio as I've ever measured on a non-turbo charged engine, and a factor which is certianly a large part of the low BSFC, output, and poor response.
I plan to solve this problem by carefully machining off the terrible intigrated exaust manifold cast into the head, welding up the low places, drilling and tapping holes near each of the 3 exposed ports, welding up the exposed water passages and possible oil return passages, then decking both surfaces of the head flat again (as the chamber side will be warped as well from the welding).
Once this is done, a proper 3-1 narrow long tube header with choke merge collector will be fabricated. From very rough calculations, this will give the engine more of a boost than haveing the IMA enguaged on full assist at all times, yet will require less fueling than before (BSFC improvement).
To sumarize, substantially improved economy and performance as well as performance potential for future modifications.
Best Wishes,
-Luke
Our beautiful valvetrain, and it's limits.
Stainless headers perchance?
I owned one and put 240K miles on it. It was good, but for whatever reasons (one was no MPG game gauge) the best I ever got was 57MPG. 
T'was a rare breed indeed. Back in the .69/g gasoline days.
